Prediction of large linear-in-k spin splitting for holes in the 2D GaAs/AlAs system

TL;DR

This paper reveals a significant linear spin splitting in 2D GaAs/AlAs holes, challenging previous assumptions based on simplified models, by employing a multi-band approach that uncovers unexpected band couplings.

Contribution

It introduces a multi-band many-body approach to accurately describe 2D hole spin splitting, revealing a large linear k-scaling previously unrecognized.

Findings

Large linear spin splitting observed in 2D holes

Standard models underestimate hole band coupling effects

Implications for low-dimensional hole spin physics

Abstract

The spin-orbit interaction generally leads to spin splitting (SS) of electron and hole energy states in solids, a splitting that is characterized by a scaling with the wavevector $\bf k$. Whereas for {\it 3D bulk zincblende} solids the electron (heavy hole) SS exhibits a cubic (linear) scaling with $k$, in {\it 2D quantum-wells} the electron (heavy hole) SS is currently believed to have a mostly linear (cubic) scaling. Such expectations are based on using a small 3D envelope function basis set to describe 2D physics. By treating instead the 2D system explicitly in a multi-band many-body approach we discover a large linear scaling of hole states in 2D. This scaling emerges from hole bands coupling that would be unsuspected by the standard model that judges coupling by energy proximity. This discovery of a linear Dresselhaus k-scaling for holes in 2D implies a different understanding of hole-physics in low-dimensions.